Shore jack



Dec. 2.0,l 195s i L. S. HOLMBOE, SR

SHORE JACK Original Filed Jam 18. 1954 IN V EN TOR.

f' 2,866,623 t Ice ratentedbeeso, 195sK SHORE `JACK Lawrence S.` Holmboe, Sr., Oklahoma City, Okla.

Original application .lanuary.18 1954, Serial No. 404,426, now Patent No. 2,762,605, dated September ,11, 1956. VDivided and this'application January 10, 1955, Serial 1 claim; (c1. 2SA- 114) The present invention relates to an improvement in shore jacks, and more particularly to shore jacks for use in shoring, bracing, jacking and scaffolding, as used ordinarily in general construction Work. It can be used as well in connection with buildings and reinforced concrete structures of all kinds, in connection with mines, in connection with braces for sewers and other trenches, in connection with scalolds and hoist towers, and in connection with like uses where such a member is desired.

The present invention is an improvement upon my device as shown in my Patent No. 2,178,792, issued November 7, 1939, for a Shore Jack. This application is a division of an application filed by me in the United States Patent Oiiice, January 18, 1954, Ser. No. 404,426, Div. 61, for Shore Jack now Patent No. 2,762,605, dated September 11, 1956. The primary objection to the use of the shore jack described and claimed in the above mentioned patent is that when considerable pressure is exerted upon the lower end of a shore member, the cam edge of the lever tends to damage and ultimately split the end portion of the shore. It is to overcome this difficulty that the present improvement was designed.

The primary object of the present invention is to provide a jacking device of this character which will not materially damage the shoring and will lift much heavier loads, and can be operated with one hand of the operator, leaving the other hand free to handle the shore and the like.

Another object is to provide a jacking device with an attached shoring protector which is always in place and ready for its intended use.

Other objects will be apparent from the following description vwhen taken in conjunction with the accompanying one sheet of drawings wherein:

Figure 1 is a perspective view of the improvement, per se;

Figure 2 is an elevational view of the device on a shoring jack in position on a shore as shown in dotted lines, and showing in dotted lines the lifting action of the jack and the device;

Figure 3 is a plan view of the device on a shoring jack; and

Figure 4 is a right side view of the device as seen in Fig. 2.

Like characters of reference designate like parts in those figures of the drawings in which they occur.

In the drawings:

The reference numeral 1 designates the lower one of a pair of shore members, and numeral 2 designates the lower end portion of the upper one, both fitting together and adapted to slide longitudinally with relation to each other while being adjusted, and being held securely thereafter by shore clamps (not shown).

The jacking device consists substantially of a one piece U-shaped pivoting collar designated, as a whole, by the numeral 5, and having a body 6 with perpendicularly outstanding arms 7 and 8. The arms 7 and 8 are provided with pivot pins 9 and 10 for holding in connection with cotter keys gripping plates 11 and 12, respectively.

On one of the arms, preferably arm 7, is an upstanding boss 13, having a perpendicularly extending pivot pin. 14. Pivotally attached on said pin 14, by a cotter key 15, is a lever 16 having an eccentric or cam head 17, the

" outer edge of said cam 17 at right angle to the lever 16 presents a transversely flat surface, as best shown at 18, Fig. 4.

The above vdescription of the jacking device is fully covered by my patent mentioned hereinabove, and is presented here only to show a workable device in connection with the present invention.

Reference numeral 20 indicates, as a whole, a pressure plate having a substantially square body 21, and an upwardly arcuate upper surface 22. However, the top surface 22 of the plate 20 may, if desired, be made flat in configuration. To the lower surface of the body 21 is rigidly attached a spaced parallel pair of depending strip rnetal legs 23 and 24, positioned edgewise longitudinally with relation to the arcuate surface 22. The spacing of the legs 23 and 24 is such that they freely receive therebetween the cam portion 17 of the lever 16.

The legs 23 and 24 are alignedly through pierced by co-operating longitudinally extending slots 25 and 26, respectively.

Each slot 25 and 26 has a width sufficient to freely receive and pivot on the pin 14, and a length great l enough to permit the cam head 17 to raise the body 21 to the uppermost part of the cam arc. The plate 20 is placed upon the cam head 17 with the legs 23 and 24 straddling the cam head and the pivot pin 14 through the co-operating slots 25 and 26, and is held in place on the pin by the cotter pin 15, Figs. 2 and 4. The area of the surface 22 is preferably substantially greater than the area of the portion of the cam contacting the lower surface of the body and less then the area of the lower end of the shore member 2. The body 21 is held in substantially a horizontal position by an integral upstanding lug 27 upon the uppermost part of the boss 13, Fig. 4. The lug 27 is substantially rectangular in general configuration, lying longitudinally parallel with and disposed vertically above the pin 14, and is narrower in width than the slot 26, as is shown in dotted lines, Fig. 3. The lug 27 extends longitudinally with the pin 14, within the slot 26, past the free edge of the arm 7, a distance substantially equal to the thickness of the leg 24. .Thus the plate 20 may pivot or rock upon the pin 14 only to the extent that the sides of the lug 27 will allow the movement of the slot 26 thereupon.

Operation The jacking device 5 is placed upon a shore 1, with the lever end 7 under the upper shore, as shown in Fig. 2. In this position the arcuate surface 22, of the pressure plate 20, is adjacent the lower end of the upper shore 2. The lever 16 is manually raised, as shown by the dotted lines in Fig. 2, and the transversely flat surface 18, of the cam head 17, contacts the lower surface of the pressure plate body 21, forcing it upwardly against the lower end of the shore 2. The purpose of the arcuate surface 22 is to insure a substantially transverse flat contact with the lower end of the shore 2, to prevent damage thereto. It is possible to lift approximately three thousand pounds with the jacking device 5 and therefore it is believed quite evident that some means such as the present improvement should be provided to protect the 'shore ends while under such pressure.

Obviously the invention is susceptible to some change or alteration without defeating its practicability, and l therefore do not wish to be conned to the preferred embodiment shown in the drawings and described herein,

further than I am limited by the scope of the Yappended claim.

I claim:

A shoring jack comprising a rigid U-shaped frame adapted to embrace a shore, plates connectedtrpivotally tothe arms of the U-framefor gnipping opposite .sides of the,shore, a boss upstanding4 fnom one of` said arms, Va pivot pin eantilevered from Asaid boss parallel tothe other armacam pivoted on said pin andrhaving an operating lever` extending therefrom; in combination, az `pressure plateihaving a substantially at under face to Contact with the surface of the cam and an upper face to engage beneath the bottom of a companion shore, a pair of legs `closely straddlingsaid earn, longitudinally slotted `to.`

pivotand slide on said pivot pin and attached at their upper ends to said pressure plate, one of said legs being positioned between said boss and the adjacent face of said Cam, `and alug projectingfrorn said boss substantially parallel to and above said pivot pin and extending through only the slot in the leg which extends between the cam and boss to hold the legs substantially normal to the plane of the U-frame when the cam is rotated to lift the pressure plate and a companion shore.

References Cited in the file of this patent UNITED STATES PATENTS 495,446 Woolcocks Apr. l1, 1893 1,553,713` Page et al Sept. l5, 1925 1,851,489 Brook Mar. 29, 1932 2,178,792 Holmboe Nov. 7, 1939 

